This application claims the benefit of Korean Application No. 2002-72848, filed Nov. 21, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a magnetron for a microwave oven, and more particularly, to a magnetron for a microwave oven in which a generation of harmonics is attenuated by changing a structure of a pole piece of the magnetron.
2. Description of the Related Art
A magnetron used as a heating source in a microwave oven, generates a microwave having a constant frequency (i.e., a fundamental wave), and at the same time, generates harmonics having a frequency of n times (wherein n is an integer) of the fundamental wave through both poles of a magnet. With regard to various ingredients of the harmonics, it has been discovered scientifically that the harmonics in a specific frequency band have caused difficulty in wireless communication and have also caused damages to the human body even though its amount is slight. With the above problems taken into consideration, the amount of the harmonics has legally been limited. Further, following the recent trend of satellite broadcasting, there has been an increase in demand to minimize the harmonics, thereby preventing interferences against the satellite broadcasting.
Conventionally, a method of suppressing generation of the harmonics while the magnetron is in operation has been employed with the use of a choke having an output structure in which the choke is mounted on the magnetron. However, the method has not been effective in attenuating the harmonics at an entire bandwidth. In addition, in order to mount the output structure to attenuate the harmonics at the entire bandwidth, the output structure has to be enlarged and becomes complicated. In this regard, the method has some limitations which have become impractical to apply.
Accordingly, it is an aspect of the present invention to provide a magnetron for a microwave oven to effectively attenuate harmonics generated by the magnetron.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious form the description, or may be learned by practice of the invention.
The foregoing and or other aspects of the present invention are achieved by providing a magnetron for a microwave oven including a yoke, an anode cylindrical body installed inside the yoke, veins mounted inside the anode cylindrical body, a filament installed in a center of the veins, and an upper magnet and a lower magnet respectively mounted on an upper side and a lower side of the anode cylindrical body. The magnetron also includes an upper pole piece and a lower pole piece respectively installed between the anode cylindrical body and the upper and lower magnets. A length from an external tip of a central part of the upper pole piece to an internal tip thereof, on which a hollow part is formed, is adjusted to suppress harmonics.
According to an aspect of the invention, the length is approximately in a range of 2.0 to 5.5 mm.